Comprehensive Guide to PHP Array Functions

This article provides a detailed overview of common PHP array functions, covering basic key‑value operations, array creation and splitting, sorting, and set operations like differences and intersections.

1. Basic key and value functions

Retrieve all keys: array_keys() Retrieve all values: array_values() Swap keys and values: array_flip() Check if a value exists: in_array() Search for a value and get its key: array_search() Check if a key exists: isset() or array_key_exists() Count elements: count() (alias sizeof())

Change key case: array_change_key_case() (CASE_UPPER / CASE_LOWER)

Count value occurrences: array_count_values() Get first/last key: array_key_first(), array_key_last() Pop last element: array_pop() Push or unshift elements: array_push(), array_unshift() Reverse array: array_reverse() Sum or product of values: array_sum(), array_product() Remove duplicate values: array_unique() Shuffle array: shuffle() Get random keys:

array_rand()

$arr_keys = array_keys($array);
$arr_values = array_values($arr);
$arr2 = array_flip($arr);
$bool = in_array('hello', $arr);
$bool = array_search('hello', $arr);
$bool = array_key_exists('a', $arr);
$n = count($arr); // same as sizeof($arr)
$lowarr = array_change_key_case($arr, CASE_LOWER);
$arr_count = array_count_values($arr);
$key = array_key_first($arr);
$last = array_pop($array);
$new_array = array_push($array, $value1, $value2, ...);
$new_array = array_unshift($array, $value1, $value2, ...);
$reverse = array_reverse($arr);
$sum = array_sum($array);
$product = array_product($array);
$bool = shuffle($arr);
$randKeys = array_rand($arr, 1);

2. Creation and splitting functions

Split array into chunks: array_chunk($array, $size, $preserve_keys) Combine two arrays into key/value pairs: array_combine($keys, $values) Fill array with keys and a common value: array_fill_keys($keys, $value) Fill array with a repeated value: array_fill($start_index, $num, $value) Merge arrays: array_merge() (non‑recursive) and array_merge_recursive() Pad array to a certain length: array_pad($array, $size, $value) Extract a slice: array_slice($array, $offset, $length, $preserve_keys) Splice array: array_splice($array, $offset, $length, $replacement) Compact variables into an array: compact($var1, $var2, ...) Extract variables from an array: extract($array) Assign array values to variables: list($var1, $var2, ...) Create a range of values:

range($start, $end, $step)

$myarr = array_chunk($arr, 2);
$arr_1 = ['A','B','C'];
$arr_2 = ['a','b','c'];
$arr_3 = array_combine($arr_1, $arr_2);
$keys = array('foo', 5, 10, 'bar');
$a = array_fill_keys($keys, 'banana');
$arr = array_fill(0, 10, 'myname');
$a = array_merge($arr_1, $arr_2);
$arr = array_pad($arr, 12, 'x');
$slice = array_slice($arr, 2, 5);
array_splice($arr, 3, 2, ['new1','new2']);
list($drink, , $power) = array('coffee','brown','caffeine');
$range = range(0,8,2);

3. Sorting functions

The primary sorting function is sort(), which can be combined with flags such as SORT_REGULAR, SORT_NUMERIC, SORT_STRING, SORT_NATURAL, and SORT_FLAG_CASE. Variants include rsort() (reverse), ksort() / krsort() (key sorting), asort() / arsort() (value sorting while preserving keys), and user‑defined sorts like usort(), uksort(), uasort(). Natural sorting functions natsort() and natcasesort() are also covered.

/* bool sort(array &$array [, int $sort_flags = SORT_REGULAR]) */

4. Array set operations

Difference: array_diff(), array_udiff(), array_diff_key(), array_diff_ukey(), array_diff_assoc(), array_diff_uassoc(), array_udiff_assoc(), array_udiff_uassoc() Intersection: array_intersect(), array_uintersect(), array_intersect_key(), array_intersect_ukey(), array_intersect_assoc(), array_intersect_uassoc(), array_uintersect_assoc(),

array_uintersect_uassoc()

$diff = array_diff($array1, $array2);
$intersect = array_intersect($array1, $array2);

This guide serves as a quick reference for developers working with PHP arrays, offering concise explanations and ready‑to‑use code snippets for each function.